session id has overwrite when i refresh sub-domain site

[eluser]guzzilar[/eluser]
[quote author="InsiteFX" date="1342098857"]Everytime you refresh a web page the session will regenerate a new session_id

Use a different session userdata field.

So as you can see checking the session_id is useless in this case.
[/quote]

Sorry i don't understand.

how can i check login session in this case. I tried use other session to check it in site.com (main-domain)
exam :

Code:

$this->session->set_userdata('member' ,'yes');

but in sub.site.com (sub-domain) session 'member' is not appear

and when i use php function

Code:

print_r($this->session->userdata);

i get userdata session array
Array ( [session_id] => a0bb64e596c072d9e271e80977059168 [ip_address] => xxx.xxx.xx.xx [user_agent] => Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.11 (K [last_activity] => 1342099551 )

What userdata session can i should.

Thank again for your reply

// I noob for session & cookie LOL